For some reason, whenever I use a record ID within a custom link or button, Salesforce is passing in the 15-character ID instead of the 18-character ID. In the past, I have coded around this on my own (using case-sensitive comparisons and substrings) but I'm now running into an issue where it's not possible to use these tricks.

Why is SF only passing the 15-character ID and how do I make it use the 18-character ID?

Thanks,
Mike